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Rezolvati sistemele:
3x+3y=0
5x-y=12

4x+3=5-3y
x-y=0

7x-y=16
3x+2y=2


Răspuns :

3x+3y=  0
5x-   y=12  l·3

 3x+3y=  0
15x-3y=36
_________
18x  /  =36 =>x=2 =>y=(-2)



4x+3-5+3y=0
  x-y=0

4x+3y=2
  x-   y=0  l·3

4x+3y=2
3x-3y=0
________
7x   /  =2 =>x=2/7 =>y=2/7


7x-   y=16  l·2
3x+2y=  2

14x-2y=32
  3x+2y= 2
_________
17x   /  =34 =>x=2 =>y=(-2)
x=2 y=-2
x=2/7 y=2/7
x=2 y=-2
Vezi imaginea DORINA490